[ios] BubbleViewController and BubbleView stubs.

ios/chrome/browser/ui/bubble/bubble_view.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/browser/ui/bubble/bubble_view.h"
+
+#include "base/logging.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface BubbleView ()
+// Label containing the text displayed on the bubble.
+@property(nonatomic, weak) UILabel* label;
+@end
+
+@implementation BubbleView
+
+@synthesize label = _label;
+
+- (instancetype)initWithText:(NSString*)text
+                   direction:(BubbleArrowDirection)arrowDirection
+                   alignment:(BubbleAlignment)alignment {
+  self = [super initWithFrame:CGRectZero];
+  return self;
+}
+
+#pragma mark - UIView overrides
+
+// Override sizeThatFits to return the bubble's optimal size.
+- (CGSize)sizeThatFits:(CGSize)size {
+  NOTIMPLEMENTED();
+  return size;
+}
+
+@end